CP4 Fuel Pump Silverado Sierra Lawsuit: Full Guide for Affected Truck Owners

The CP4 fuel pump Silverado Sierra lawsuit centers on widespread complaints from owners of Chevrolet Silverado HD and GMC Sierra HD diesel trucks equipped with certain Duramax engines. These complaints focus on sudden fuel system failure allegedly caused by the Bosch CP4 high pressure fuel pump, a component used in several late model GM heavy duty trucks. Owners claim the pump’s design is incompatible with U.S. diesel fuel, leading to catastrophic engine failure, expensive repairs, and safety risks. This guide explains the lawsuit in detail, including the mechanics behind the CP4 pump issue, affected models, legal allegations, costs of failure, and what owners can do now.

Understanding the CP4 Fuel Pump Issue

What the CP4 Pump Is

The Bosch CP4 pump is a high pressure fuel pump used in many modern diesel engines. Its purpose is simple: raise fuel pressure to extremely high levels so the engine can perform cleanly, efficiently, and with maximum power.

However, the CP4 has a known weakness. The pump relies on ultra-low sulfur diesel (ULSD) sold in the United States, which has lower lubricity than European diesel fuel. Lower lubricity can cause internal metal-on-metal wear inside the pump.

How Failure Happens

When the CP4 pump begins to wear down, it produces fine metal shavings. These metal particles circulate through the entire fuel system, often destroying:

• Fuel injectors

• Fuel rails

• Fuel lines

• Fuel filters

• The fuel tank

This is often referred to as “fuel system contamination.” Once metal spreads, the entire system may need replacement.

See More: Japan Car Seat Laws: Complete 2025 Guide for Parents and Travelers

Why Silverado and Sierra Owners Are Filing Lawsuits

The CP4 fuel pump Silverado Sierra lawsuit argues that GM installed a pump that was known to be prone to failure in the U.S. diesel environment. The lawsuits claim:

• GM used the pump even though evidence existed of potential failure in other brands.

• GM marketed the trucks as heavy-duty and reliable despite the alleged defect.

• Failures occur without warning, putting drivers in unsafe situations.

• Repairs often exceed $8,000–$12,000, and warranty claims are frequently denied.

Alleged Safety Risks

Many complaints describe:

• Loss of power on highways

• Sudden engine stalling

• Loss of steering and braking assistance

• Hazardous situations while towing

Affected Silverado and Sierra Models

The lawsuits most commonly reference the following models:

Owners of these trucks report similar patterns of CP4 failure, though additional model years may eventually be included depending on legal findings.

Common Symptoms of CP4 Fuel Pump Failure

While failure often occurs suddenly, many owners report warning signs before the complete breakdown.

Top Warning Signs

1. Hard starting

2. Long cranking

3. Sudden loss of power

4. Rough idle

5. Engine misfires

6. Check engine light with fuel pressure codes

7. Metallic dust found in fuel filters

Diagnostic Trouble Codes (DTCs) Commonly Reported

• P0087 – Fuel Rail/System Pressure Too Low

• P0088 – Fuel Rail/System Pressure Too High

• P0191 – Fuel Rail Pressure Sensor Range/Performance

• P0093 – Fuel System Large Leak Detected

These codes often accompany early CP4 wear.

Costs Associated With CP4 Failure

When a CP4 pump fails, it can contaminate the entire system. Repairs are typically costly because diesel injection components are precision machined and cannot simply be cleaned.

Typical Repair Costs

• Replacement CP4 pump: $1,500–$2,000

• Injectors (all): $3,000–$4,500

• Fuel rails and lines: $1,000–$1,500

• Fuel tank cleaning or replacement: $600–$1,200

• Labor: $1,000–$2,500

Average Total: $8,000–$12,000+

Many owners report paying out of pocket after warranty denial.

See More: Japan Car Seat Laws: Complete 2025 Guide for Parents and Travelers

Core Allegations in the CP4 Fuel Pump Silverado Sierra Lawsuit

1. Defective Design

Plaintiffs argue the CP4 pump was not designed for American ULSD fuel, leading to increased failure rates.

2. Knowledge of Prior Failures

Other automakers such as Ford experienced CP4 failures years earlier. Plaintiffs claim GM had access to this data.

3. Warranty Denials

Numerous owners report that GM classifies CP4 damage as “fuel contamination,” not a component defect, and denies repairs under warranty.

4. Misrepresentation of Duramax Reliability

The lawsuit argues that GM advertised the Duramax as reliable for towing, hauling, commercial work, and long-term durability, despite knowing of CP4 issues.

Evidence Supporting the Lawsuit Claims

Multiple sources build the foundation for the legal allegations:

Industry Trends

• CP4 failures reported across Ford, Ram, Audi, Volkswagen, and other brands using similar pumps.

Fuel Standard Differences

• U.S. diesel has lower lubricity than European diesel—an issue widely documented.

Owner Complaints

• Thousands of real-world reports on automotive forums, dealerships, repair centers, and NHTSA filings.

Technical Service Bulletins (TSBs)

• GM issued diagnostic bulletins that acknowledge symptoms consistent with CP4 failure.

Steps Silverado and Sierra Owners Can Take

Below is a practical list for owners who suspect CP4 issues.

Immediate Actions After Suspected Failure

1. Stop driving the truck to prevent deeper contamination.

2. Document all symptoms and warning lights.

3. Retrieve OBD-II error codes.

4. Photograph any metallic material found in fuel filters.

5. Save all service records.

Long Term Protection Measures

1. Use reputable diesel fuel providers.

2. Replace fuel filters early and consistently.

3. Drain and maintain the water separator.

4. Maintain detailed logs for future legal use.

5. Monitor for hard starting or fuel pressure irregularities.

Legal Options for Affected Owners

Owners of Silverado and Sierra trucks with CP4 related failures may consider:

• Joining an existing class action

• Filing an individual claim

• Seeking reimbursement for prior repairs

• Reporting the failure to NHTSA to support ongoing investigations

Legal professionals use detailed documentation, service history, and mechanical evidence to support claims.

Can Owners Still Recover Compensation?

Many lawsuits remain active, and new cases are being reviewed. Attorneys evaluate:

• Whether the truck suffered CP4 failure

• Whether evidence of metal contamination exists

• Whether the warranty was denied

• Whether the truck fits model years under investigation

Even if repairs occurred years ago, compensation may still be possible depending on legal outcomes.

FAQs:

1. What is the main claim behind the CP4 fuel pump Silverado Sierra lawsuit?

The primary claim is that GM installed a CP4 pump that was not compatible with U.S. diesel fuel, leading to premature failure and costly repairs.

2. Does a CP4 failure always destroy the entire fuel system?

In most cases, yes. Once metal particles circulate through the system, injectors, rails, and lines become contaminated.

3. How can I confirm if my Silverado or Sierra uses a CP4 pump?

Most 2011–2016 Duramax engines use the CP4.2 pump. A VIN check or dealer service record can confirm the component.

4. Will GM replace the CP4 pump for free?

Many owners report warranty denials, which is why lawsuits emerged. Resolution depends on legal outcomes.

5. Are upgraded fuel pumps available?

Yes. Some aftermarket companies offer CP3 conversion kits, which replace the CP4 with a more robust design.

Conclusion:

The CP4 fuel pump Silverado Sierra lawsuit continues to draw attention as more truck owners experience costly fuel system failures and safety risks linked to the CP4 pump. With growing reports of engine damage, repair expenses, and performance issues, the CP4 fuel pump Silverado Sierra lawsuit underscores the importance of understanding how the CP4 pump works, why it fails, and what legal options are available. As additional owners join the Silverado and Sierra CP4 fuel pump lawsuit, documenting evidence, recognizing early failure symptoms, and knowing your rights can significantly strengthen your case. Staying informed empowers affected Silverado and Sierra drivers to pursue the compensation they deserve and navigate the CP4 fuel pump Silverado Sierra lawsuit with confidence and clarity.